1. Field of the Invention
The present invention is related to a rotary machine for a vehicle having a magnetic field pole core to which claw poles, a field coil and a permanent magnet are secured.
2. Description of the Related Art
In order to reduce leakage of magnetic flux from the magnetic field pole cores, a rotor of an alternating current generator having claw poles and magnetized permanent magnets disposed between the claw poles is disclosed in Japanese Patent Application Laid Open No. Sho 61-85045 filed by the applicant. The permanent magnets are magnetized before they are secured to the pole cores in the same direction as the claw poles are magnetized by the field coil. Thereafter, claw poles are lathed or machined to have an appropriate air gap and/or rotational balance of the rotor. For the same purpose, Japanese Patent Application Laid Open Sho 54-116610 discloses another alternating current generator having a rotor on which claw poles, a field coil and unmagnetized magnets are secured. The magnets are magnetized after the rotor and the stator have been assembled by supplying magnetizing current to the field coil of the generator.
However, when the rotor of the former generator is machined or lathed, chips or iron powder adhere to or are attracted to the rotor since the rotor is magnetized by the permanent magnets disposed therein, thereby causing various problems, such as rotor halting and its resultant engine stall. While the latter generator may solve the above problems, magnetizing force is limited by the field coil and is not enough to reduce the leakage of the magnetic flux from the pole cores.